Semiaquatic Bugs Research Articles

A fossil water measurer from the mid-Cretaceous Burmese amber (Hemiptera: Gerromorpha: Hydrometridae)

AbstractSemiaquatic bugs (Hemiptera: Gerromorpha) comprise about 1,800 extant species classified in eight families. So far, 38 fossil species belonging to six families have been described or recorded, most of Cenozoic age. Knowledge about the evolutionary history of the major groups of Gerromorpha is seriously hampered by the scarcity of well-preserved Mesozoic fossils, especially from the Cretaceous. The present paper reports on a well-preserved semiaquatic bug from amber collected in the northern part of Myanmar (Burma). The source of this fossiliferous amber was previously considered to be Eocene in age, but recent evidence indicates that it originated in the Middle Cretaceous (Turonian-Cenomanian), or 100-90 Ma. The fossil species is described as Carinametra burmensis gen. et sp. n. The presence of three pairs of cephalic trichobothria, a prolonged head, long slender antennae and legs, reduced wing venation, etc., places the fossil in the gerromorphan family Hydrometridae or water measurers. Other characters suggest a close relationship with the two extant genera of the most basal of the hydrometrid subfamilies, Heterocleptinae. We present and discuss the available evidence used in the dating of Burmese amber. Finally, we discuss the phylogenetic, paleobiological, and biogeographic significance of the new fossil.

Water striders from the Paleogene of Denmark with a review of the fossil record and evolution of semiaquatic bugs (Hemiptera, Gerromorpha)

Journal of Zoological Systematics and Evolutionary ResearchVolume 38, Issue 2 p. 128-128 Water striders from the Paleogene of Denmark with a review of the fossil record and evolution of semiaquatic bugs (Hemiptera, Gerromorpha) F. Wiese, F. Wiese BerlinSearch for more papers by this author F. Wiese, F. Wiese BerlinSearch for more papers by this author First published: 21 May 2002 https://doi.org/10.1046/j.1439-0469.2000.3821183.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume38, Issue2June 2000Pages 128-128 RelatedInformation

The coral treaders, Hermatobates Carpenter (Hemiptera : Hermatobatidae), of Australia and New Caledonia with notes on biology and ecology

Semiaquatic bugs (Heteroptera, infraorder Gerromorpha) are distributed worldwide with approximately 1,600 described species. Most species live in various types of freshwater habitats, but a little more than 10% have colonised the marine environment. The Australian fauna constitutes a significantly higher percentage of marine species (about 25%) than in any other continent. Among these are the coral treaders, Hermatobates Carpenter, belonging to the Hermatobatidae, one of very few insect families that only include marine species. In this paper the two species of Hermatobates previously known from Australia are redescribed and H. armatus, sp. nov. from the Chesterfield Islands in the Coral Sea is added. The distribution of species known from Australia and New Caledonia is mapped, and a revised key to the eight species currently recognised in the genus is presented. Finally, the available knowledge about the biology and ecology of coral treaders is reviewed and discussed.

Fossil water striders in the Oligocene/Miocene Dominican amber (Hemiptera: Gerromorpha)

AbstractMost water striders and other semiaquatic bugs (Hemiptera, Gerromorpha) live on the surface film of freshwater. Adults are often flightless and are therefore not prone to be caught in resin exuded by trees on land and subsequently preserved as amber inclusions. Nevertheless, a small number of gerromorphan bugs have so far been reported from amber. The present paper reports on six species of Gerromorpha in the Oligocene/Miocene Dominican amber, describing Brachymetroides atra gen. et sp. n. (Gerridae: Charmatometrinae), Microvelia grimaldii sp.n. and M. electra sp.n. (Veliidae: Microveliinae) and redescribing Electrobates spinipes Andersen & Poinar (Gerridae: Electrobatinae), Microvelia polhemi Andersen (Veliidae: Microveliinae), and Halovelia electrodominica Andersen & Poinar (Veliidae: Haloveliinae). Finally, the phylogenetic, palaeobiological, and biogeographic significance of these amber fossils are discussed.

New approach for habitat characterization based on species lists of aquatic and semiaquatic bugs

A new approach is proposed for the environmental impact assessment of fresh waters. New indices and the cenological values of aquatic and semiaquatic bug (Hemiptera) species have been obtained through multivariate analysis based on the species list of 157 localities in Hungary. The 45 species involved in this study can be characterized by their preference for habitat types on a linear scale ranging from small, shallow waters to large, deep waters. The habitats themselves can be characterized by the added cenological values of the species found.

Patterns of postmating reproductive isolation in a newly discovered species pair, Aquarius remigis and A. remigoides (Hemiptera; Gerridae)

Aquarius remigoides Gallant and Fairbairn has recently been described as specifically distinct from A. remigis (Say) based upon genetic and morphological data. Both species are common, semiaquatic bugs (Hemiptera; Gerridae) found on the surface of streams and small rivers. Allozyme studies have shown them to be more distantly related than most other congeneric species in the Gerridae, with significant barriers to gene flow where their ranges abut. We assess postmating reproductive isolation between A. remigoides and A. remigis, using a bracket cross design with five sampling sites along a north–south cline traversing the hybrid zone. We also report the results of long-distance conspecific crosses of A. remigis, using populations from California and Quebec. Neither these nor the intraspecific bracket crosses reveal any evidence of isolation by distance within species. However, heterospecific crosses show significantly reduced fertility, hatching success, survival of both sexes to eclosion (final moult) and percentage of males. Egg production is not influenced by cross type, and we found no evidence of hybrid sterility in either sex. Analyses of genotypic frequencies at three isozyme loci in eight hybrid and 22 pure populations reveal significant deficiencies of heterozygotes in hybrid populations. The proportion of males is also significantly lower in hybrid populations than in pure populations. The laboratory and field results indicate that postmating isolation between these two species occurs in the form of severe reductions in both the fertility of heterospecific crosses and the viability of hybrids, particularly hybrid males. Genetic mechanisms for Haldane's rule and asymmetries in the reciprocal heterospecific crosses are discussed.

Conflicts of interest between the sexes: a study of mating interactions in a semiaquatic bug

Abstract. Mating behaviour can be expected to reflect a compromise between the conflicting interests of the two sexes. Adults of the water strider, Aquarius remigis, mate many times over a period of several months, and males often remain mounted for several hours following sperm transfer. Conflict between the sexes is indicated by both pre-mating and post-mating struggles. To determine the relative influence of males and females on the frequency and duration of mating, 548 mating interactions were videotaped in the laboratory and an additional 140 interactions were observed under more natural, field conditions. Mating attempts were initiated by males, but most of these attempts were resisted by females. The duration of pre-mating struggles initially increased and then declined as the number of mating attempts increased, suggesting possible mate assessment by females at low levels of harassment, but convenience polyandry at higher levels. Long pre-mating struggles were associated with unsuccessful matings. Matings that were long enough to allow sperm transfer were characterized by short pre-mating struggles and long post-mating struggles. Post-mating struggles invariably resulted in the male being dislodged. Depriving males of mates for 7 days prior to the trials increased the number of mating attempts and the durations of the pre- and post-mating struggles, but did not significantly influence the frequency or duration of mating. These results confirm male incentive to increase the frequency and duration of mating, but indicate that female resistance effectively limits both parameters.

Biology of Water Striders: Interactions Between Systematics and Ecology

The hemipteran infraorder Gerromorpha, or the semiaquatic bugs, includes approximately 1500 species that occupy the adaptive zone defined by water surfaces. Most species occur on freshwater, but several lineages have colonized marine habitats, and others have become secondarily terrestrial. These bugs are conspicuously adapted for life on the surface film, especially with respect to locomotion, feeding, reproductive behavior, and life history (2). Their two-dimensional habitats make semiaquatic bugs ideal subjects for behavioral studies, and their striking patterns of wing polymorphism have challenged life-history enthusiasts since early in the century. Since Andersen's (2) comprehensive review a decade ago, over 200 papers about gerromorphans have appeared, setting the stage for new approaches in comparative biology. In this review, we cover the literature about gerro­ morphans appearing since 1980, emphasizing work on broader evolutionary themes. We aim to provide a synthesis useful to research workers and to underscore the advantages of using gerromorphans in ecological and behav­ ioral studies. We also illustrate the interactions now possible among sys-

Introgressive hybridization in Heteroptera: the example of Limnoporus Stål (Gerridae) species in western Canada

Populations of the pondskaters, Limnoporous dissortis and Limnoporous notabilis, hybridize extensively in the Cordilleran region of western Canada. In laboratory crosses using L. dissortis from central Alberta and L. notabilis from southwestern British Columbia, most eggs are fertilized and begin development, but only ca. 50% of the eggs hatch and nearly all F1 hybrid adults are males. F1 hybrid males are fertile in backcrosses to females of both species, although egg hatch is reduced and mainly male progeny result from crosses to females of the paternal species. These species both have an XO sex chromosome system, and the foregoing results suggest that either products of genes on X chromosomes of the two species are incompatible or that they are incompatible with heterospecific cytoplasmic elements. Males of L. dissortis are more successful at interspecific copulations than are those of L. notabilis, perhaps because they more frequently adopt aggressive mating behaviour that circumvents premating barriers. Although gene pools of these two species are partially isolated by both pre- and post-mating barriers, there has been large-scale exchange of genes at autosomal loci, and significant introgression occurs over a large geographic area. Introgression is asymmetric, with genes of L. dissortis tending to flow disproportionately into L. notabilis populations, reflecting differences between the species in mating behaviour and dispersal tendencies. Because these two species are not closest relatives, I conclude that reticulations can be important considerations in the evolution of semiaquatic bugs. A literature survey shows that interspecific hybridization occurs in a number of heteropteran families, although partial barriers to gene flow are common.

Change in Photoperiodic Sensitivity during Hibernation in a Semi-Aquatic Bug, Microvelia douglasi (Heteroptera : Veliidae)

Timing of induction of reproductive diapause of Microvelia douglasi were investigated. Diapausing females began to appear in early September in field population. Under laboratory condition at 24°C, reproductive diapause was induced by photoperiods shorter than 12.5 hr of light, which concides with the daylength in early September. Seasonal changes in the pattern of egg production of overwintering females incubated under laboratory conditions at 24°C were also examined. When the insects were incubated under 16L-8D photoperiod, almost all the females began to lay eggs irrespective of the sampling date. When incubated under 12L-12D and 8L-16D, the percentage of females which laid eggs was low in samples collected before December, but it became as high as 100 percent in samples collected after December. The preoviposition period from the date of the collection increased until the end of October, decreased to 5 to 6 days in lae December and stayed at a constant level thereafter. Although females incubated under 16L-8D continued to lay eggs throughout experimental period, some females, which were incubated under 12L-12D and 8L-16D, stopped laying eggs soon after beginning of incubation. However, under 12L-12D, the percentage of such females decreased in samples collected later in the winter.

The effects of predators on habitat use, activity and mating behaviour of a semi-aquatic bug

The effects of predators on habitat use, activity and mating behaviour of a semi-aquatic bug

Food-Sharing vs Monopolising Prey: A Form of Kleptoparasitism in Velia Caprai (Heteroptera)

Kleptoparasitic behaviour in the stream-living semiaquatic bug Velia caprai (Tam.) was studied in laboratory experiments. Prey weighing 7.9 mg) and the number of V. caprai feeding simultaneously on it. Large prey animals always attracted several individuals. When five equally hungry individuals were allowed to attack a large prey I found significant negative regressions between attack order and weight increase and attack order and time spent feeding. Ingestion rate showed a significant positive regression with attack order. The second attacker tended to increase in weight as much as the first but tended to have a higher ingestion rate. When individuals of three different hunger levels were allowed to attack a large (> 7.9 mg) prey, the most hungry ones attacked first.

Field observations on the activities of a group-living semiaquatic bug, Velia caprai

Field observations on the activities of a group-living semiaquatic bug, Velia caprai

AQUATIC AND SEMIAQUATIC HEMIPTERA OF PEATLANDS AND MARSHES IN CANADA

AbstractThirteen families containing 138 species of aquatic and semiaquatic Hemiptera have so far been recorded from Canada. The identification of these presents few real difficulties and so the general occurrence of the taxa across the country is fairly well known. Although there has been no intensive study of the Hemipterous insects in peatlands and marshes, the 61 species so far reported from marshes, 32 from fens, and the 33 from bogs appear to be facultative rather than obligatory inhabitants of these habitats. All have been found in other habitats and probably most lentic species occur in marsh habitats. All aquatic and semiaquatic bugs are predators, and most overwinter as adults. Environmental–physiological study of species occurring in bogs has just begun, but evidence suggests that many species have the ability to regulate their internal milieu in water with pH below 4.6–4.7. However, further experiments are needed to determine the physiological limits of tolerance of these insects, the details of osmotic and ionic regulation, and acid–base balance in low-pH water. More collecting is needed in bogs, fens, and marshes, and the life cycle and biology of the Hemiptera occurring in peat-lands still require intensive study.

Structure, function and evolution of the reproductive system in females of Hebrus pusillus and H. ruficeps (hemiptera, gerromorpha, hebridae).

Females of Hebrus pusillus and H. ruficeps have two ovaries of five telotrophic ovarioles each, two lateral oviducts, a common an intricate sperm storage and delivery system, the gynatrial complex, and a short, tubular ovipositor. The skeletomusculature of this system is fully described in both species and its functions (summarized in Figs. 55-66) reconstructed from study of living bugs, dissections, whole mounts and serial sections. To mate, a male H. pusillus jumps on the back of a female, induces her to lower her ovipositor, and, within 12 min (at 18-24°C), introduces the endosoma of his phallus up its shaft and fills his seminal duct with sperm. The female draws this into her gynatrial sac at the end of copulation and transfers it into her spermatheca in about 30 min (both sperm and spermatheca are longer than the female's body). A single, large egg passes from an ovariole into the vagina where its apex is temporarily lodged in a fertilization chamber. Spermatozoa are drawn from or swim out of the spermatheca into a grooved fecundation canal in the roof of the vagina and forward to the micropyle of the egg. After fertilization, the egg enters the base of the ovipositor and is deposited. The gynatrial complex of female, semiaquatic bugs probably evolved to accommodate the fertilization of the proportionately larger eggs of a lineage of bugs ancestral to Gerromorpha that was being selected for small body size and was then modified to increase the role of the female in controlling fertilization of eggs.

Water Absorption by Eggs and Serosal Specialization as Clues to Evolutionary Trends in Heteroptera

Water absorption by eggs, expressed by increase in fresh egg weight, was observed in Notonecta triguttata Say, Gerris lacustris latiabdominis Miyamoto, and G. gracilicornis gracilicornis Horvath. In these aquatic and semiaquatic bugs, whose eggs develop in water, serosal specialization at the posterior egg pole (columnar serosa) occurs. Close association was observed between onset of water absorption by the eggs and that of embryonic growth. Fresh weight of the developing eggs hardly changed in Hygia opaca Uhler, the eggs of which develop on damp ground, whereas it decreased steadily in Scotinophora lurida Burmeister and Coptosoma punctissimum Montandon, whose eggs develop on plant leaves. Serosal specialization at the posterior egg pole was never observed in these terrestrial bugs. Rearing of these heteropteran eggs under unusual cultural conditions and topical application of a microcauterizer at the columnar serosa in G. paludum insularis Motschulsky suggested that water absorption by the eggs was necessary to ensure enough oxygen to the embryos. Occurrence of serosal specialization and resulting water absorption by the eggs are considered from the viewpoint of heteropteran evolution.

Mating Reduces Predation on Male Milkweed Beetles

Previous articleNext article No AccessNotes and CommentsMating Reduces Predation on Male Milkweed BeetlesDavid E. McCauley, and Ellen C. LawsonDavid E. McCauley Search for more articles by this author , and Ellen C. Lawson Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 127, Number 1Jan., 1986 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284472 Views: 4Total views on this site Citations: 21Citations are reported from Crossref Copyright 1986 The University of ChicagoPDF download Crossref reports the following articles citing this article:Madison Hernandez, Paul Masonick, Christiane Weirauch Crowdsourced online images provide insights into predator-prey interactions of putative natural enemies, Food Webs 21 (Dec 2019): e00126.https://doi.org/10.1016/j.fooweb.2019.e00126P. A. Lagos A review of escape behaviour in orthopterans, Journal of Zoology 303, no.33 (Sep 2017): 165–177.https://doi.org/10.1111/jzo.12496Danilo G. Muniz, Glauco Machado Experimental limitation of oviposition sites affects the mating system of an arachnid with resource defence polygyny, Animal Behaviour 109 (Nov 2015): 23–31.https://doi.org/10.1016/j.anbehav.2015.08.007Taís M. Nazareth, Glauco Machado, Claude Wicker-Thomas Egg Production Constrains Chemical Defenses in a Neotropical Arachnid, PLOS ONE 10, no.99 (Sep 2015): e0134908.https://doi.org/10.1371/journal.pone.0134908Gustavo S. Requena, Glauco Machado Lack of costs associated with nest-related behaviors in an arachnid with exclusive paternal care, Oikos 124, no.33 (Sep 2014): 372–380.https://doi.org/10.1111/oik.01641Amanda M. Franklin, Zoe E. Squires, Devi Stuart-Fox, Therésa M. Jones Does Predation Risk Affect Mating Behavior? An Experimental Test in Dumpling Squid (Euprymna tasmanica), PLoS ONE 9, no.1212 (Dec 2014): e115027.https://doi.org/10.1371/journal.pone.0115027Giovanni Benelli, Gabriele Gennari, Alessandra Francini, Angelo Canale Longevity costs of same-sex interactions: first evidence from a parasitic wasp, Invertebrate Biology 132, no.22 (May 2013): 156–162.https://doi.org/10.1111/ivb.12017Stephen F. Matter Abundance of an Herbivorous Beetle: Factors Affecting Dispersal and Local Reproduction, The American Midland Naturalist 162, no.11 (Jul 2009): 19–28.https://doi.org/10.1674/0003-0031-162.1.19Maria Almbro, Cecilia Kullberg The downfall of mating: the effect of mate-carrying and flight muscle ratio on the escape ability of a pierid butterfly, Behavioral Ecology and Sociobiology 63, no.33 (Oct 2008): 413–420.https://doi.org/10.1007/s00265-008-0675-4Stephen F. Matter Changes in landscape structure decrease mortality during migration, Oecologia 150, no.11 (Jul 2006): 8–16.https://doi.org/10.1007/s00442-006-0491-3Rickey D. Cothran Precopulatory mate guarding affects predation risk in two freshwater amphipod species, Animal Behaviour 68, no.55 (Nov 2004): 1133–1138.https://doi.org/10.1016/j.anbehav.2003.09.021O. Y. Martin, D. J. Hosken Copulation reduces male but not female longevity in Saltella sphondylli (Diptera: Sepsidae), Journal of Evolutionary Biology 17, no.22 (Dec 2003): 357–362.https://doi.org/10.1046/j.1420-9101.2003.00668.xQiao Wang, Wenyu Zeng , Environmental Entomology 33, no.33 ( 2004): 657.https://doi.org/10.1603/0046-225X-33.3.657L. M. Hanks INFLUENCE OF THE LARVAL HOST PLANT ON REPRODUCTIVE STRATEGIES OF CERAMBYCID BEETLES, Annual Review of Entomology 44, no.11 (Jan 1999): 483–505.https://doi.org/10.1146/annurev.ento.44.1.483Gary A. Polis, Joseph D. Barnes, Mary K. Seely, Joh R. Henschel, Margit M. Enders PREDATION AS A MAJOR COST OF REPRODUCTION IN NAMIB DESERT TENEBRIONID BEETLES, Ecology 79, no.77 (Oct 1998): 2560–2566.https://doi.org/10.1890/0012-9658(1998)079[2560:PAAMCO]2.0.CO;2Carin Magnhagen Predation risk as a cost of reproduction, Trends in Ecology & Evolution 6, no.66 (Jun 1991): 183–186.https://doi.org/10.1016/0169-5347(91)90210-O Andrew Sih , James Krupa , and Steven Travers An Experimental Study on the Effects of Predation Risk and Feeding Regime on the Mating Behavior of the Water Strider, The American Naturalist 135, no.22 (Oct 2015): 284–290.https://doi.org/10.1086/285044Darryl T. Gwynne Does copulation increase the risk of predation?, Trends in Ecology & Evolution 4, no.22 (Feb 1989): 54–56.https://doi.org/10.1016/0169-5347(89)90144-4BENGT GUNNARSSON Local adjustment of sex ratio in the spider Pityohyphantes phrygianus, Journal of Zoology 217, no.11 (Mar 2009): 1–7.https://doi.org/10.1111/j.1469-7998.1989.tb02470.xAndrew Sih The effects of predators on habitat use, activity and mating behaviour of a semi-aquatic bug, Animal Behaviour 36, no.66 (Nov 1988): 1846–1848.https://doi.org/10.1016/S0003-3472(88)80129-5Kikuo IWABUCHI Mating Behavior of Xylotrechus pyrrhoderus BATES (Coleoptera : Cerambycidae) : IV. Mating Frequency, Fecundity, Fertility, and Longevity, Applied Entomology and Zoology 23, no.22 (Jan 1988): 127–134.https://doi.org/10.1303/aez.23.127

Phylogenetic Inference as Applied to the Study of Evolutionary Diversification of Semiaquatic Bugs (Hemiptera: Gerromorpha)

Andersen, N. M. (Zoological Museum, University of Copenhagen, Universitetsparken 15 DK-2100 Copenhagen, Denmark) 1979. Phylogenetic inference as applied to the study of evolutionary diversification of semiaquatic bugs (Hemiptera: Gerromorpha). Syst. Zool. 28:554578.-The possibility of deciphering patterns of evolutionary diversification using the semiaquatic bugs (Hemiptera: Gerromorpha) as an example group is examined. Two different approaches are contrasted: the evolutionary systematic and the phylogenetic (cladistic) approach. The methods of phylogenetic inference are thereafter applied to data on the structural, behavioral, and ecological divesity of semiaquatic bugs. Semiaquatic bugs comprise an unusual life form as they are the most successful group of insects inhabiting the water surface in almost any kind of habitat, including the open ocean. Semiaquatic bugs are currently classified in eight families: Mesoveliidae, Hebridae, Paraphrynoveliidae, Macroveliidae, Hydrometridae, Hermatobatidae, Veliidae, and Gerridae. A cladogram of relationships among these families is constructed. It provides a hypothesis about the sequence of branching in evolution corroborated by synapomorphic characters. An estimate of the amount of evolutionary change within single lineages (derivation load) is introduced. The habitat preferences of semiaquatic bugs are superimposed upon the cladistic relationships among taxa. Phylogenetic inferences suggest that the ancestral type of habitat of most families was humid terrestrial and/or marginal aquatic. Species belonging to most families have remained in the ancestral habitats and a few species of the Veliidae and Cerridae have secondarily invaded similar habitats. Derived habitats include the plant-covered water surface, the free surface of stagnant fresh water, flowing fresh water, intertidal marine waters, and the surfage of the open ocean. Each of these categories of habitats has been independently invaded several times from more ancestral habitats. Several adaptive features of semiaquatic bugs are discussed and their ancestral and derived states separated. There are definite associations between the physical nature of the environment and the structural, mechanical, and behavioural elements of locomotion. The evolutionary transition from the walking rhythm of leg movements towards the rowing rhythm and locomotion by jump-and-slide movements has probably taken place several times. Two different kinds of predator strategies in semiaquatic bugs can be distinguished: that of a searching predator, which is the most ancestral, and that of a waiting predator utilizing surface ripples in prey-location, which is the derived strategy. Wing polymorphism, sexual behaviour of surface-inhabiting bugs, and diversification of the egg system are also discussed. The evolutionary diversification of semiaquatic bugs is visualized as a repeated series of transitions between a hygropetric and a pleustonic adaptive zone and adaptive radiation towards various subzones of the latter. This model has some weaknesses from an ecological point of view. Ecological diversification is not just a problem of the relations between structure and environment. The limited supply of resources, conflicting demands of various factors, and interspecific competition and/or predation may be important as well. In conclusion, the neo-Darwinian views on the origin and differentiation of higher taxa are examined and criticized. [Phylogenetic inference; adaptive zones; habitat preferences; adaptation; semiaquatic bugs.]

Phylogenetic Inference as Applied to the Study of Evolutionary Diversification of Semiaquatic Bugs (Hemiptera: Gerromorpha)

Phylogenetic Inference as Applied to the Study of Evolutionary Diversification of Semiaquatic Bugs (Hemiptera: Gerromorpha)

Laboulbeniales on Semiaquatic Hemiptera. III. Rhizopodomyces

Thaxter's original description of Rhizopodomyces is emended to reflect new information gained from a study of not only the type species, R. merragatae, but also of six additional species described as new, R. basifurcatus, R. californicus, R. erectus , R. geniculatus, R. mexicanus, and R. polhemusii. All of the species have been found on semiaquatic bugs of the family Hebridae (Hemiptera). The female thallus of Rhizopodomyces spp. consists of a simple, two-celled receptacle, the suprabasal cell bearing a one-celled primary appendage and giving rise usually to a single, longstalked perithecium. The male thallus initially consists of three cells , a twocelled receptacle and a terminal cell which may form a simple antheridium directly or remain sterile and form a simple appendage, in which case the suprabasal cell of the receptacle divides and forms one or two simple antheridia directly. Rhizopodomyces is compared with several other dioecious genera of Laboulbeniales of similar morphology, Amorphomyces, Dioicomyces, Dicrandromyces, Triandromyces, and Tetrandromyces. Speculations regarding the possible relationship of Rhizopodomyces to these genera are presented.